Dynamics of larval populations ofSchistosoma mansoniinBiomphalaria glabrataII

Abstract

Two schemes of production occur during the larval development of Schistosoma mansoni in the intermediate host Biomphalaria glabrata: one of cercariae and one of sporocysts of a higher order than II (see text). In the production of cercariae there are successive maturing waves of larval stages. These lead to the formation of several generations of cercariae which are responsible for the variations in cercarial production observed during the patent period of snail infection. The dynamics of the production of sporocyst producers of sporocysts is integrated into the dynamics of cercarial production by a greater multiplication at the end of each generation of cercariae. These additional generations of sporocysts ensure the rejuvenation of the sporocyst population throughout the parasitism of the snail by replacing the deficient sporocyst producers of cercariae.